Could we have something like Dataview’s this.file.day?

[Moonbase59]

Is your feature request related to a problem? Please describe.
Dataview has this.file.day, which returns a date if …

• something "looking like a date" (must not be in YYYY-MM-DD format) is found in the file’s title, or
• a date: YAML frontmatter variable has been set

and undefined (in the form of a settable text replacement like -) otherwise.

This is extremely convenient, since one doesn’t have to fiddle with separating dates out of oddly-formatted file names, or can use YAML date: as a (preferred) equivalent.

Describe the solution you'd like
A similar file variable in Templater, that uses the same rules. If it was too much to set an undefined replacement text in settings, it might have an additional, optional parameter that provides that (having a good default).

Describe alternatives you've considered
Tried to somehow intermix Dataview and Templater to achieve same result, but that’s too complicated. Also, requiring two instead of one plugin isn’t always optimal.

Additional context
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